Instrument barrel



FIG. 1 is a perspective view of my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines showing the writing tip housing in FIGS. 1-5 and 7 and the features on the push button in FIGS. 1, 2, 4, and 5 are included for the purpose of illustrating portions of the instrument barrel that form no part of the claimed design. 

CLAIM The ornamental design for an instrument barrel, as shown and described. 